The present invention relates to apparatus for converting a stream of sheets, groups of sheets or analogous commodities into discrete stacks of overlapping commodities, especially for converting a continuous stream of partially overlapping identical imprinted sheet-like commodities into discrete stacks wherein the neighboring commodities are in accurate register with each other.
It is already known to utilize a rotary separating element for interception of one of more oncoming signatures, discrete sheets or analogous commodities (hereinafter called sheets for short) upon completion of the assembly of a stack consisting of a predetermined number of sheets. The stream is supplied by one or more endless belts or analogous conveyors, and successive foremost sheets are caused to descend onto a platform where the sheets accumulate to form a stack. The separating element is located at the discharge ends of the conveyors and is caused to enter the path of an oncoming sheet when the platform accumulates a given number of sheets. Means is provided to withdraw the separating element as soon as the fully assembled stack is lifted off or otherwise removed from the platform.
In certain presently known apparatus, the separating element is mounted on a rotary shaft and is further movable up and down. Such complex movements of the separating element necessitate the provision of a rather complicated drive which is not only expensive but also prone to malfunction. Moreover, each insertion of the separating element into the path of oncoming sheets necessitates a full revolution of the shaft and a complete up-and-down movement of the element. The frequency of movements of the separating element into and out of the path of oncoming sheets is limited owing to inertia of moving parts so that the output of apparatus embodying the just described separating elements is not entirely satisfactory, especially in modern printing plants for newspapers, books, brochures or the like.